1. Field of the Invention
The present invention generally relates to an illumination device and a manufacture method thereof. Particularly, the present invention relates to an illumination device and a manufacture method thereof to prevent the formation of overly concentrated light.
2. Description of the Prior Art
Display panels and display devices using the display panels gradually become a mainstream among a variety of display devices. For example, home flat-panel TVs, panel monitors of personal computer and laptop computer, and display screens of mobile phone and digital camera are products which use a great deal of display panels. Particularly, the market demand for the liquid crystal display device rises rapidly in recent years. The design of backlight module for liquid crystal display device becomes diverse in order to fulfill the requirement of function and appearance.
For the pursuit of lighter weight, smaller dimension, and less power consumption, light-emitting diode (LED) devices have been largely used as the light source. Either edge-lighting or bottom-light backlight module can use LEDs as the light source. FIG. 1 shows a conventional LED element. As FIG. 1 shows, the conventional LED device includes a base 10, on which a light-emitting diode (LED) chip 20 is disposed. On the base 10 a sealant 30 is provided to cover the LED chip 20. The surface of the sealant 30 is usually formed as a convex surface.
Due to the geometric properties of convex surface, light is easily centralized in a forward direction of the LED device. When such a design is combined with the backlight module, the characterization of light centralizing results in local spot phenomenon that affects the image quality of the display device. In order to overcome the problem, it is usually to increase the light mixing distance in the backlight module and the overall thickness is accordingly increased. Another way to overcome the problem is increasing the quantity of diffuser plate in the backlight module that adversely increases the overall thickness and the cost.